Forecaster Simon Keeling, of website Weather Online, posted: "There is the possibility of a breakdown into more unsettled conditions through the middle and later stages of the month, thanks to the westerly winds breaking through for a time as the high pressure retreats.

"It is possible that a significant snow event may occur for a few days mid month as the milder Atlantic air battles with the cooler continental air."

The last official white Christmas was in 2010, when snow was widespread across Northern Ireland, Scotland, parts of Wales, the Midlands, north-east and far south-west England.

A Met Office spokesman said: "For many people, a white Christmas means a complete covering of snow falling between midnight and midday on December 25.

"However, the definition used most widely, notably by those placing and taking bets, is for a single snowflake (perhaps among a mixed shower of rain and snow) to be observed falling in the 24 hours of December 25 at a specified location.

"We can accurately forecast if snow is likely on any given Christmas Day up to five days beforehand.

"In terms of the statistical likelihood of snow based on climatology, we know that a snowflake has fallen on Christmas Day 38 times in the last 52 years, therefore we can probably expect more than half of all Christmases to be a 'white Christmas' in this sense.

"Snow lying on the ground on Christmas Day - as we would expect from typical Christmas scene - is much rarer.

"There has only been a widespread covering of snow on the ground (where more than 40 per cent of stations in the UK reported snow on the ground at 9am) four times in the last 51 years.